Helmet retention system



FIG. 1 is a front perspective view of a helmet retention system inaccordance with our new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a left-side elevational view thereof; and,

FIG. 5 is a right-side elevational view thereof.

The broken lines immediately adjacent the shaded areas represent thebounds of the claimed design while all other broken lines are directedto environment and are for illustrative purposes only; the broken linesform no part of the claimed design.

CLAIM The ornamental design for a helmet retention system, as shown anddescribed.